The lowest point below the rest position of a wave is called the trough. The highest point above the rest position is called the crest.
the lowest is a trough and the highest is a crest.
The point in which the wave is at rest or is at its resting state.
the rest position, or where it stops
a body is said to be at rest if it does not change its position with time with respect to a reference point
if a body do not change its position with time as compared to a reference point then the body is said to be in rest
The height of the wave, above the rest position, is its Amplitude. Twice the amplitude is the distance from the deepest point to the highest point.
The maximum potential energy is at the top of each swing and is at its minimum at the bottom of the swing when it is perpendicular to a horizontal surface. The maximum kinetic energy is at the bottom of the swing, and is at its minimum at the top of each swing. Please refer to the related link below for an illustration.
'An object said to be at rest when it is not in motion'.The above statement has been proved by Newton's First Law of Motion (Law Of Inertia) , it says When a body is at rest it tends to be at rest and when a body is inmotion it tends to be in motion until an external force is applied on it.
from the point at rest the line will be curved and going diagonally upwards visual: http://www.gravitywarpdrive.com/General_Relativity_Images/Falling_Ball_Graph_Distance.gif
The correct term from the maximum displacement from the rest position in a wave is the Amplitude (A).
Rest
The answer is rest